Carrier-current relay



5, 1950 H. w. LENSNER 2,519,258

CARRIER CURRENT RELAY Filed July 22, 1948 WITNESSES: INVENTOR 26% Herbert; Lensner. 77% M (9m ATTORNEY Patented Aug. 15, 1950 UNITED STATES PATENT OFFICE CARRIER- CURRENT RELAY Application July 22, 1948, Serial No. 40,085

4 Claims. (01. 175-294) My invention relates to an improvement in the plate-keyed carrier-current protective-relaying system which is described and claimed in an application of Bernard .E. Lenehan, Serial No. 599,832, filed June 16, 1945, patented September 14, 1948, No. 2,449,490. This Lenehan application related particularly to other uses functions of a carrier-current relaying system for protecting transmission-lines against faults, said other uses functions being carrier-current functions other than transmission-line protection, and usually meaning telemetering or voice-communication control, or both, although there are many other other uses to which protective-relay carrier-current equipment is put, during normal fault free line conditions. Some occasional trouble has been experienced, in the actual use of this Lenehan system, indicating that the tripping-contacts of the sensitive third-zone impedance-relay are being overburdened, so that it has been necessary or desirable to redesign the circuits in which these contacts are located.

The object of my present invention is to provide an improved control-circuit for the oscillatortube of a carrier-current protective-relay system of a type which uses keying, or carrier-starting control, in the plate-circuit of the oscillator, having two plate-keyed carrier-controlled circuits, one for the protective relays, and the other for other uses such as a telemetering key.

A more specific object of my invention is to eliminate the use of two independent carrierstarting circuits, to eliminate the necessity for an auxiliary relay (K3 in the Lenehan application) to interrupt the other uses keying-circuit during a fault, to effect a material reduction in the current-load onthe tripping contacts of the sen-' sitive third-zone impedance element which is used for carrier-starting duty, and to provide a circuit in which the coils of auxiliary relays or contactor-switches (which are used to show whichsensitive fault-responsive relay has operated, and to provide additional fault-responsive relay-contacts) will never be impressed with a current which is more than two times the pickupvalue of the relay, instead of being impressed with anywhere from two tosix times the pickupvalue as in the Lenehan circuit.

With the foregoing and other objects in View, my invention consists in the systems, circuits, apparatus, combinations, methods, and parts, hereinafter described and claimed, and, illustrated in the accompanying drawing, the single figure of which is a somewhat simplified diagrammatic view of circuits and apparatus illustrating my invention in an illustrative form of embodiment.

In the drawing, my invention is illustrated as being applied to the protection of a 3-phase cycle transmission-line section I, having phases A, B, and C. The line-section I is connected to a bus 2 through a circuit breaker 3, having an auxiliary make-contact 3a, and having a tripcoil TC.

The usual, or any desired, protective relays are provided, having alternating-current circuits which are shown diagrammatically, in a box 4, as being energized from a line-voltage potentialtransformer 5 and a line-current transformer 6. These protective relays are preferably of the instantaneous variety, and they include a set of directional elements, which are shown at DA, DB, DC and DO, for the three line-phases and for ground-currents or zero-sequence currents, respectively. The protective relays are also illustrated as comprising two sets of distancerelays and ground-current relays, corresponding roughly to the second and third zones of distance-response, reaching out to second-zone faults, which are located beyond the far end of the protected line-section l, and to third-zone faults which are still more remote. The two zones of distance-responses are indicated by the numerals 2 and 3, the phase-fault distance-elements being indicated as being of the impedancetype or modified-impedance type, as indicated by the letter Z, while the ground-fault faultdetector elements are indicated as overcurrent residual-current relays of different sensitivities, as indicated at I92 and I03. The impedance elements are designated as ZZA, Z2B, ZZC, 23A, Z3B and Z3C for the various line-phases and distance-zones.

The same letters and numerals of designation are applied to the various relay-contacts, which are shown elsewhere on the drawing, in the various direct-current circuits which are shown in the form of an across-the-line direct-current diagram. The physical connections between the separated parts of the various relays are also symbolically indicated by arrows. The relays are shown in their deenergized positions.

My present invention concerns the control and operation of carrier-current apparatus, which is shown as comprising a transmitter T and a receiver R. The transmitter T comprises a master-oscillator tube CS0, and two amplifier-tubes Al and A2. The receiver R. comprises a receiver detector-tube REC. The output-circuits of the power-amplifier tubes Al and A2, and the controlalso other refinements which are not shownon the simplified diagram of my drawing.

The oscillator CS is provided with a cathodecircuit 7, a plate-circuit 8, and a control-grid circuit 9. given to the protective relays by me'ans of. two back-contacts CSG and CEP, which normall-y connect the oscillator cathode-circuit l to the negative battery-terminal The relays CSG and CSP are auxiliary directionally responsive ground-fault and phaseiault relays, respectively, which are provided with correspondingly lettered actuating-coils 05G and CSP, which are sho-wn near the top of the direct-current connections of the "drawingf l hus, the CSG-coil is energized-in a circuit traceable from the positive battery-termirial through the DO ground-directional make-contact and the It? ground-fault makecontact, to a directional ground-fault relayingci'rcuit- H, and thence 'thr'cugi the CSG-cail to the negative battery-terminal The (ESP-coil i'stenergized from. a directional phase-fault relaying-circuit i2, which is energized from any one of three circuits, corresponding to the three'linephaseseach energizing-circuit comprising a directi'onal element,'such as DA, and a secondzon'e impedance-element of-the same phase, such as that indicatedatZtA.

' The illustrated relaying-system utilizes ground fault preference, which was provided bylme'ans of a CSG make-contact, which "is connected inparallel with the CSP back-contactfas indicated at I3, which will be well understood by those skilled in theart.

The oscillatorgrid-circuit is connected, to the negative battery-terminal through a gridleak resistorGL, and. it is also connected to a tunedloircuit l4, which includes a varioineter L3 and three capacitors C2, C3 andC l. This tuned circuit is. also connected to the oscillator platecir'cuit. B'thrlough a blocking capacitorCS. 'Ihis tuned-circuit is further connected-to the amplifier control-grid circuits 24 and ZZ'through block-'- ing. capacitors C6 andIC't. Theamplifier eontrol-gridcircuitsJE l and-22 are connected, through gridresistors 'GL i and GL2, to a common amplitier, grid circuit 23, which is directly connected to thenega'tive bus I The two. amplifier cathode-circuits are connected together, as indicated at 21%, and thence are. connected, through a cathode-drop. resistor R], to the oscillator cathod'e-circuitl. The cathode-resistor Rl thus makes thepower-arnplifier cathodemircuit 24 normally operate at a pate-h ti'al which is more positive than the negative bus 6) by the voltage-drop in the cathode resistor R1! The oscillator plate-circuit 8receives its directcurrent energization through a radio-frequency Preferential carrier-stopping control is 4 R2, and thence to a carrier-starting circuit 26. The carrier-starting circuit 26 is connected to the positive bus through any one of six circuits, containing the six normally open contacts, as follows, namely, the four make-contacts of the sensitive protective relays ZEA, 23B, 23C, and I03, the telemetering contacts (or other telemetring control-means), which are, diagrammaticallyindicated at TM, and a test push button PB which can initiate carrier-current transmission for test-purposes. The four carrier-starting protective-relay contacts Z3A, 23B, Z30 and IE3 are used to energize four individual relay-circuits 28-A, 28 B, 28C, and 280 from the positive bus through the corresponding relay-contacts, and these four relay-circuits 28-A to 28 are connected to the carrier-starting circuit 2t through individual rectifiers 29, there being a separate rectifier for each of these four circuits, the polarity of the rectifier being such as to permit current to fiowonlyfrom the bus through the corresponding relay-contacts ZiA, Z3 B, ZSC or I03, as the case may be, through the associated rectifier 29, and hence to the carrierstarting circuit- 26.

Practically all--carriercurrent relaying systems require, for various purposes, more contacts than can be placed on the sensitive fault-responsive relays ZSA, 23B, 23C and I53, without grossly overburdening these relays and definitely interfering with their sensitivity to small fault currents. It has been customary, therefora to provide auxiliary relays or co-ntactoif-switches, which I- have marked KA, KB, KC-and KO, respectively, for providing these additional or auxiliary relay-contacts, most of which are not shown in the attacheddrawing, because most of these auriliary relay-contacts relate to relaying purposes other than the carrier-current control toward which my present inventionis. directed. My presentim vention involves the use of the special circuits 28A, 28-13, 28 8 and zii o for energizingthe operating-coils KB, KC and KO- of the correspondingly lettered: auxiliary-relays, the same lettering: being applied to the auxiliary relays-and to their coils and their. contacts, in accordance with theinvention which already been explained. These relay-coils KA, KB, KC and K0 are connected between the several relay-circuits it-A, 28-3, 28--Cand- 28-4), and the negative bus through individualresistors R-A, R-B, RFC-andRe-O, respectively.

The receiver-tubeREC has itscathode-circuit 3U energized from a potentiometer 3| which is connected acros's the battery-terminals and The plate-circuit 32' of the receiver REC is connected to the positive. battery-terminal through. amillianimeter or-other telemetering device 33, and. a receiver relay holding-coil RRl-I. The receiver-relay also has an operating or tripping coil RR, whi'clri's shown in the lower quarter of the diagram, in a shunt-circuit connected across the carrier-stopping back-contacts CSG and CSP, so that-said receiver rel'a-y RR is energized whenever carrier-current-transmission is stopped by a relaying operation. However, the receiver-relay RR cannot respond to its operating or tripping-coilfRR, mm; carrier-current is no longer received from the far-endline-terminal or terminals, at which time the receiver-relay holding-coil RRH- ceases to be energized from the receiver-tube REC, and the receiver-relay thenoperatesto close its two make-contacts RB which are utilized a to connect the directionalre laying circuits H and- #2; respectively, to the tripping-circuit 35 for tripping the circuit breaker 3, through a circuit which includes the breaker-contact 3a, and the trip-coil TC.

Since the receiver-relay tripping-coil RR is connected in shunt across the carrier-stopping back-contacts CSG and CSP, it is also connected between the oscillator cathode-circuit I and the negative battery-terminal This coil RR has a moderately high resistance, or it has a resistor R3 connected in series with it. The cathode-circuit l is also connected to an auxiliary positive-potential fault-responsive circuit 36, through a still larger resistor R4, which cooperates with the resistor R3 to constitute a voltagedivider which prevents the oscillator OSC from oscillating whenever the relaying carrier-stopping cathode-circuit is opened at either the CSG or CSP back-contacts. The auxiliary positivepotential fault-responsive circuit 36 is connected to the positive bus through any one of tour parallel-connected make-contacts KA, KB, KC or KO of the previously described auxiliary relays bearing the corresponding letters.

In the oscillator-circuits, a capacitor CHI is connected between the positive terminal 25 of the plate-choke RFC and the cathode-circuit I, for the purpose of providing a radio-frequency impedance which is low, as compared to the 1mpedance of the plate-resistor R2 which is connected to the carrier-start bus 26. In this way, I reduce, to a negligible amount, any change in the oscillator-frequency, regardless of whether the carrier-current transmission is started by means of one of the four fault-responsive elements Z3A, 2313, Z30 or I03, or by the telemetering-control TM.

In the power-amplifier circuits, a capacitor CH2 is connected in shunt across the cathoderesistor Rl, that is, it is connected between the amplifier cathode-circuits 24 and the oscillator cathode-circuit 1. This capacitor 012 serves to suppress parasitic oscillations which might otherwise tend to occur because of the continuous energization of the amplifier-tubes Al and A2.

While I have described an illustrative equipment at only one terminal of the protected linesection I, it will be understood, of course, that the same, or similar, equipment will, or may, be provided at the other terminal or terminals of the protected line-section.

In operation, the oscillator-tube CS is normalljy deenergized, while the power-amplifier tubes A! and A2 are normally energized. Under these circumstances, the carrier-circuit transmitter 'I is not transmitting, because oscillations are not being generated by the oscillator-tube OSC.

In the operation of the novel or characteristic carrier-starting circuits of my present invention, it will be noted that the rectifiers 29 interpose practically no resistance in the carrier-starting circuit, when carrier-current transmission is being started by means of any one of the four faultresponsive relays Z3A, ZBB, Z30 and IE3. However, except for currents flowing toward the carrier-starting circuit 26, the rectifiers 29 substantially isolate the four individual relaying-circuits 28-A, 28-13, 28-0 and 28--O from each other and from the carrier-starting bus 26 so that it is no longer necessary to provide two separate carrier-starting buses, one for the protective-relay contacts Z3A, 2313, Z36 and I03, and the other for the telemetering contacts TM, as was the case in the Lenehan system.

Furthermore, since the four relaying-circuits 28-A, 28-B, 28C, 28-0 are substantially insulated from each other by the four rectifiers 29, each, of these relaying-circuits can be used to energize the operating-coil of its own auxiliary relay KA, KB, KC or KO, as the case may be, so that the current through any one of these relay-coils KA, KB, KC or K0 is dependent only upon its own energizing-circuit, and is not at all dependent upon how many other fault-responsive energizing-circuits may have been simultaneously energized, so as to simultaneously energize a plurality of the relay-coils KA, KB, KC and KO. This avoids the difliculty, in the Lenehan' system, wherein the amount of current which flowed through each of the coils KA, K3, K0 and KO depended upon how many others or these coils were energized at the same time, thus making it extremely difficult to successfully design these coils so that the relay would pick up, regardless of whether its energizing-current was anywhere from two to six times the minimum pickup-current which would barely energize the relay. In my system, this energizing-current will always be 200%, or any other fixed safe percentage which is over the pickup-value.

At the same time, the rectifiers 29 effectually isolate the coils of the auxiliary relays KA, KB, KC and KO from the telemetering contacts TM, so that no additional burden is placed on these telemetering contacts by the auxiliary relays.

The particular carrier-current relaying-system which is illustrated in the drawing is of a type in which, as previously described, it is nec essary for the carrier-current transmission to be interrupted at both or all terminals of the protected line-section I, in order to deenergize the receiver-relay holding-coil RRI-I, which permits the receiver-relay tripping-coil RR to actuate the receiver-relay and close its two make-contacts RR and RR, in the two tripping-circuits which are responsive, respectively, to the groundfault and phase-fault directional relaying buses l l and i2, shown near the top of the figure. To this end, it is necessary for the carrier-stopping protective-relay contacts CSG and CSP to have complete control over the stoppage of carriercurrent transmission, regardless of what carrier-starting contacts may be closed, whether the protective-relay carrier-starting contacts Z3A, 23B, ZSC, I03, or the test push button PE, or the telemetering contacts TM.

It is accordingly necessary for the relaying carrier-stop contacts CSG and CSP to be in cluded somewhere in the direct-current energizetion-circuits of the oscillator-tube 080, as by being placed either in series with the common platesupply circuit 25, or the plate-circuit 8, or the cathode-circuit I, or otherwise, as by biasing the control-grid 9, or detuning or interrupting one of the essential tuned circuits or output-circuits or the oscillator-tube 080. In the particular system illustrated in the drawing, the cathodecirouitcarrier-stopping connection is shown, because of certain inherent advantages therein, but it is to be understood that I am not limited to this particular showing.

In the illustrated system, the relaying carrierstopping contacts CSG and CSP are also included in series with the cathode-circuits 24 of the amplifier-tubes AI and A2, so as to altogether deenergize said amplifier-tubes at all times when the protective relays call for a stoppage of carrier-current transmission, thus taking no chances of parasitic transmitter-oscillations during an ail-9 instant when it is necessary to be absolutely sure .cflan; interruption of carrier-current transmissionfin order to obtain a correct tripping-operation ofthe line circuit breaker 3. The inclusion of' the relaying carrier-stopping contacts. CSG and CSB in series with the. cathode-circuits 1 and 2 4 of the transmitter-tubes, while the grid-potential circuits. are coupled back to the. negative bus is advantageous in providing an additionai l2-volt negative bias on the grid-circuits 9i andJZBQ-as, a result of the 12,-vo1t arcing-voltage which-appears across the carrier-stopping. contacts CSG or CS-P, when they open in the process of interrupting the cathode-currents of the transmitter-tubes, as described and claimed in a Lenehan et a1, Patent 2,255,934, granted Septemberlfi, 19i1.

While I; haveiillustrated my invention, and described its modeof operation, in particular referenceto a single illustrative form of embodiment, I wish it to be understood that. many changes in details and arrangement are possible, asithe various features of the invention are applicable to different kinds of carrier-current protective relaying-systems, whichare also used for another use or uses, other than transmission-line protection. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A plural-purpose carrier-current relayingsystem for protecting a transmission-line section, and alsoat times performing a function other than protecting the line-section, said system comprising a carrier-current transmitter comprising an oscillator-tube having a cathode tube-circuit means and aplate tube-circuit means for supplying said oscillator-tube with direct-current energization, one of saidtube-circuits comprising a plurality of parallel-connected control-means, each including a circuit-making means for applying a direct-current carrier-starting energizing-voltage to said tube-circuit, at least one of said parallel-connected control-means being a part of a means for performing the protectiverelay function and another of said parallel-connected control-means being a part of a means for performing said other function, at least one of Said parallel-connected control-means including a serially connected rectifier in such polarity as to permit substantial current-flow only in the carrier-starting direction.

2. A plural-purpose carrier-current relayingsystem for protecting a transmission-line section, and also at times performing a function other than protecting the line-section, said system com.- prising a carrier-current transmitter comprising an oscillator-tube having a cathode tube-circuit means and a plate tube-circuit means for supplying said oscillator-tube with direct-current energization, said plate tube-circuit comprising a plurality of parallel-connected control-means, each including. a circuitemaking means for applying a direct-current carrier-starting energizingvoltage to said, plate tube-circuit, at least one of said parallelconnected. control-means being a part of a means for performing the protectiverelay functionand another of, said parallel-connected'control-means being apart of ameansfor performing said. other function, at least. one, Of said. parallel-connected control-means including a serially connectedrectifier in such polarity as to perm-it substantial current-flow only in the. carrier-starting direction.

3.. A. plural-purpose carrier-current relaying.- systemfor protecting atransmission-line section, and also at times performing a function other than protecting the line-section, said system comprising a plurality of separate, protective-relay control means'ea'ch havingits own circuit-making means for. applying a. direct-current carrierstarting voltage toits own individual protectiverelay circuit, aplurality of separate auxiliary relay-means each having. a control-means energized from a separate one of said individual pro.- tective-relay circuits, a carrier-current transmit.- ter comprising. an oscillator-tube having a. oath.- ode tube-circuit means and a plate. tube-circuit means for supplying said oscillator-tube. with directecurrent energization, one of. said tube-circuits compr-ising; an other function controlmeans having a circuit-making means for applying a direct-current carrier-starting energizingvoltage to said tube-circuit, and. a pluralityof rectifiers for separately connecting each. of said several protective-relay circuits to the, tube-circuit which is energized by said other function? control-means, the polarities ofsaid rectifiersbeing, such as to permit substantial. current-flow only; in the carrier-starting direction.

4. A plural-purpose carrier-current relaying system for protecting a transmission-line section, and also at times performing a, function other than protecting the line-section, said system comprising a plurality of separate protective-relay control-means, each having, its own circuit-making meansfor applying, a: direct-current. carrierstarting voltage to its. own. individual protective.- relay circuit, a plurality of. separate auxiliary relay-means; each having acontrol-means energized. fronra separate oneof saidindividualprotective-relay circuits, a carrier-current transmit.- ter comprising an; oscillator-tube havinga cath-r ode tube-circuit means and a plate tube circuit means for supplying said. oscillator-tube with direct-current energization, saidplate tube-circuit comprising an other function control meanshavinga circuit making mean's for. apply.- ingv a. direct-current. carrier-starting energizing voltage to said plate tube-circuit, andia. plurality of rectifiers for. separately connectingeach ofsaid several protectiverelay circuits. tosaid'plate tubecircuit, the. polarities ofjsaild, reotifiers, being such asto permit substantial. currenteflovv only. in the carrier-starting direction.

' HERBERT W. LENSNER.

nnrnnnnons CITED The following references are of, record inthe file of: this patent:

UNITED STATES PATENTS Number Name Date 2,112,228 Crago Mar. 29, 1938 2,210,679 Lenehan Aug. 6", 1940 2,372,078 Goldsborough Mar. 20, 1945 2,449,490 Lenehan Sept. 14, 1948 

